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Shock CJ, Stevens MJ, Frischknecht AL, Nakamura I. Molecular dynamics simulations of the dielectric constants of salt-free and salt-doped polar solvents. J Chem Phys 2023; 159:134507. [PMID: 37795785 DOI: 10.1063/5.0165481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 09/15/2023] [Indexed: 10/06/2023] Open
Abstract
We develop a Stockmayer fluid model that accounts for the dielectric responses of polar solvents (water, MeOH, EtOH, acetone, 1-propanol, DMSO, and DMF) and NaCl solutions. These solvent molecules are represented by Lennard-Jones (LJ) spheres with permanent dipole moments and the ions by charged LJ spheres. The simulated dielectric constants of these liquids are comparable to experimental values, including the substantial decrease in the dielectric constant of water upon the addition of NaCl. Moreover, the simulations predict an increase in the dielectric constant when considering the influence of ion translations in addition to the orientation of permanent dipoles.
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Affiliation(s)
- Cameron J Shock
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA
| | - Mark J Stevens
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Amalie L Frischknecht
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Issei Nakamura
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA
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Woodcox M, Mahata A, Hagerstrom A, Stelson A, Muzny C, Sundararaman R, Schwarz K. Simulating dielectric spectra: A demonstration of the direct electric field method and a new model for the nonlinear dielectric response. J Chem Phys 2023; 158:124122. [PMID: 37003751 DOI: 10.1063/5.0143425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
We demonstrate a method to compute the dielectric spectra of fluids in molecular dynamics (MD) by directly applying electric fields to the simulation. We obtain spectra from MD simulations with low magnitude electric fields (≈0.01 V/Å) in agreement with spectra from the fluctuation-dissipation method for water and acetonitrile. We examine this method's trade-off between noise at low field magnitudes and the nonlinearity of the response at higher field magnitudes. We then apply the Booth equation to describe the nonlinear response of both fluids at low frequency (0.1 GHz) and high field magnitude (up to 0.5 V/Å). We develop a model of the frequency-dependent nonlinear response by combining the Booth description of the static nonlinear dielectric response of fluids with the frequency-dependent linear dielectric response of the Debye model. We find good agreement between our model and the MD simulations of the nonlinear dielectric response for both acetonitrile and water.
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Affiliation(s)
- Michael Woodcox
- Theiss Research, P. O. Box 127, La Jolla, California 92038, USA
| | - Avik Mahata
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899, USA
| | - Aaron Hagerstrom
- Communications Technology Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Angela Stelson
- Communications Technology Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Chris Muzny
- Material Measurement Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Ravishankar Sundararaman
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180, USA
| | - Kathleen Schwarz
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899, USA
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Zeplichal M, Gies J, Bernd J, Winslaws DK, Chang T, Chen YS, Strauss SH, Boltalina OV, Terfort A. Fluorinated Azaacenes: Efficient Syntheses, Structures, and Electrochemical Properties. J Fluor Chem 2022. [DOI: 10.1016/j.jfluchem.2022.109960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Electrical conductivity variations of aqueous NaCl solutions with microwave field: A molecular dynamics study. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Patel LA, Yoon TJ, Currier RP, Maerzke KA. NaCl aggregation in water at elevated temperatures and pressures: Comparison of classical force fields. J Chem Phys 2021; 154:064503. [PMID: 33588550 DOI: 10.1063/5.0030962] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The properties of water vary dramatically with temperature and density. This can be exploited to control its effectiveness as a solvent. Thus, supercritical water is of keen interest as solvent in many extraction processes. The low solubility of salts in lower density supercritical water has even been suggested as a means of desalination. The high temperatures and pressures required to reach supercritical conditions can present experimental challenges during collection of required physical property and phase equilibria data, especially in salt-containing systems. Molecular simulations have the potential to be a valuable tool for examining the behavior of solvated ions at these high temperatures and pressures. However, the accuracy of classical force fields under these conditions is unclear. We have, therefore, undertaken a parametric study of NaCl in water, comparing several salt and water models at 200 bar-600 bar and 450 K-750 K for a range of salt concentrations. We report a comparison of structural properties including ion aggregation, hydrogen bonding, density, and static dielectric constants. All of the force fields qualitatively reproduce the trends in the liquid phase density. An increase in ion aggregation with decreasing density holds true for all of the force fields. The propensity to aggregate is primarily determined by the salt force field rather than the water force field. This coincides with a decrease in the water static dielectric constant and reduced charge screening. While a decrease in the static dielectric constant with increasing NaCl concentration is consistent across all model combinations, the salt force fields that exhibit more ionic aggregation yield a slightly smaller dielectric decrement.
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Affiliation(s)
- Lara A Patel
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Tae Jun Yoon
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Robert P Currier
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Katie A Maerzke
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Sayer T, Cox SJ. Macroscopic surface charges from microscopic simulations. J Chem Phys 2020; 153:164709. [PMID: 33138409 DOI: 10.1063/5.0022596] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Attaining accurate average structural properties in a molecular simulation should be considered a prerequisite if one aims to elicit meaningful insights into a system's behavior. For charged surfaces in contact with an electrolyte solution, an obvious example is the density profile of ions along the direction normal to the surface. Here, we demonstrate that, in the slab geometry typically used in simulations, imposing an electric displacement field D determines the integrated surface charge density of adsorbed ions at charged interfaces. This allows us to obtain macroscopic surface charge densities irrespective of the slab thickness used in our simulations. We also show that the commonly used Yeh-Berkowitz method and the "mirrored slab" geometry both impose vanishing integrated surface charge densities. We present results both for relatively simple rocksalt (1 1 1) interfaces and the more complex case of kaolinite's basal faces in contact with an aqueous electrolyte solution.
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Affiliation(s)
- Thomas Sayer
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Stephen J Cox
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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Saric D, Kohns M, Vrabec J. Dielectric constant and density of aqueous alkali halide solutions by molecular dynamics: A force field assessment. J Chem Phys 2020; 152:164502. [PMID: 32357782 DOI: 10.1063/1.5144991] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The concentration dependence of the dielectric constant and the density of 11 aqueous alkali halide solutions (LiCl, NaCl, KCl, RbCl, CsCl, LiI, NaI, KI, CsI, KF, and CsF) is investigated by molecular simulation. Predictions using eight non-polarizable ion force fields combined with the TIP4P/ε water model are compared to experimental data. The influence of the water model and the temperature on the results for the NaCl brine are also addressed. The TIP4P/ε water model improves the accuracy of dielectric constant predictions compared to the SPC/E water model. The solution density is predicted well by most ion models. Almost all ion force fields qualitatively capture the decline of the dielectric constant with the increase of concentration for all solutions and with the increase of temperature for NaCl brine. However, the sampled dielectric constant is mostly in poor quantitative agreement with experimental data. These results are related to the microscopic solution structure, ion pairing, and ultimately the force field parameters. Ion force fields with excessive contact ion pairing and precipitation below the experimental solubility limit generally yield higher dielectric constant values. An adequate reproduction of the experimental solubility limit should therefore be a prerequisite for further investigations of the dielectric constant of aqueous electrolyte solutions by molecular simulation.
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Affiliation(s)
- Denis Saric
- Thermodynamics and Energy Technology, University of Paderborn, 33098 Paderborn, Germany
| | - Maximilian Kohns
- Laboratory of Engineering Thermodynamics, Technische Universität Kaiserslautern, 67633 Kaiserslautern, Germany
| | - Jadran Vrabec
- Thermodynamics and Process Engineering, Technical University Berlin, 10587 Berlin, Germany
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Seal S, Doblhoff-Dier K, Meyer J. Dielectric Decrement for Aqueous NaCl Solutions: Effect of Ionic Charge Scaling in Nonpolarizable Water Force Fields. J Phys Chem B 2019; 123:9912-9921. [PMID: 31647235 PMCID: PMC6875873 DOI: 10.1021/acs.jpcb.9b07916] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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We investigate the dielectric constant and the dielectric decrement of aqueous NaCl
solutions by means of molecular dynamic simulations. We thereby compare the performance
of four different force fields and focus on disentangling the origin of the dielectric
decrement and the influence of scaled ionic charges, as often used in nonpolarizable
force fields to account for the missing dynamic polarizability in the shielding of
electrostatic ion interactions. Three of the force fields showed excessive contact ion
pair formation, which correlates with a reduced dielectric decrement. In spite of the
fact that the scaling of charges only weakly influenced the average polarization of
water molecules around an ion, the rescaling of ionic charges did influence the
dielectric decrement, and a close-to-linear relation of the slope of the dielectric
constant as a function of concentration with the ionic charge was found.
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Affiliation(s)
- Sayan Seal
- Gorlaeus Laboratories, Leiden Institute of Chemistry , Leiden University , PO Box 9502, 2300 RA Leiden , The Netherlands
| | - Katharina Doblhoff-Dier
- Gorlaeus Laboratories, Leiden Institute of Chemistry , Leiden University , PO Box 9502, 2300 RA Leiden , The Netherlands
| | - Jörg Meyer
- Gorlaeus Laboratories, Leiden Institute of Chemistry , Leiden University , PO Box 9502, 2300 RA Leiden , The Netherlands
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Affiliation(s)
- Stephen J. Cox
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Michiel Sprik
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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Castañeda Medina A, Schmid R. High Order Compact Multigrid Solver for Implicit Solvation Models. J Chem Theory Comput 2019; 15:1293-1301. [DOI: 10.1021/acs.jctc.8b00774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Arcesio Castañeda Medina
- Computational Materials Chemistry Group, Lehrstuhl für Anorganische Chemie 2, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Rochus Schmid
- Computational Materials Chemistry Group, Lehrstuhl für Anorganische Chemie 2, Ruhr-Universität Bochum, 44780 Bochum, Germany
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